I don't agree. I believe Rationals (NT's) are aware of illogical possibilities within a given situation, but simply prefer not to entertain them. Just as Idealists (NF's) are aware of emotionally unsavory possibilities in a given situation and prefer not to entertain them.
In other words, they each have limitations in different areas. My guess is that it's people who are more aware of possibilities
before making a judgment on them who are the freest thinkers. Those would probably be Ne-dominant ENxP's. And trust me, it shows in their behavior.
I would give NT's the advantage in determining truth, however. Logic is more well-suited to discovering truth in the long run, although it's process may prevent a person from discovering or creating an idea that doesn't seem to connect with what is already understood until the steps to it are built up from the foundation. NF's might be better at finding isolated pockets of knowledge at times that NT's wouldn't consider looking for because it didn't fit at all with what they already knew to be true.